How Gut Bacteria Protect The Brain

Gut Bacteria and Brain Health

The blood-brain barrier (BBB) acts as a gatekeeper, protecting the brain from various toxic elements while allowing the entrance of various life-sustaining nutrients like water, glucose, amino acids, and gases that are essential for the function of the brain. It is formed by cells that line the capillaries and are connected by what are called “tight junctions,” quite similar to the tight junctions in the cells that line the gut.

Any number of brain disorders is associated with breakdown of the BBB including infections, and even cancer. And as such, scientists have aggressively studied the BBB to determine specifically what leads to increased permeability and, perhaps most importantly, what can be done to reduce permeability in other words what can be done to reestablish the barrier, and protect the brain.

In a stunning new research report appearing in the journal, Science Translational Medicine, researchers at the Karolinska Institute in Stockholm studied the blood brain barrier in mice that were “germ free.” That means, that the mice used in this experiment did not have bacteria living within their intestines. Using highly sophisticated brain scanning technology, the researchers demonstrated that the blood brain barrier in these mice was significantly compromised, basically a situation of what we may call a “leaky brain,” and this leakiness of the barrier persisted into adulthood.

Even more compelling was their finding that when these mice received a fecal transfer, meaning that their intestines were inoculated with the fecal material including bacteria from a healthy mouse, the permeability of the blood brain barrier was markedly improved.

First, this research is groundbreaking. The implications of being able to manipulate the health of the blood brain barrier by making changes in the gut bacteria offers up for the first time a powerful therapeutic tool that may have incredibly wide application in brain disorders. Professor Sven Pettersson, the principal investigator involved in the study was quoted in Science Daily as stating:

Given that the microbiome composition and diversity change over time, it is tempting to speculate that the blood-brain barrier integrity also may fluctuate depending on the microbiome. This knowledge may be used to develop new ways for opening the blood-brain-barrier to increase the efficacy of the brain cancer drugs and for the design of treatment regimes that strengthens the integrity of the blood-brain barrier.

Second, this research adds further evidence to the notion that a wide array of human health issues may well depend upon the diversity and complexity of the array of bacteria that lives within the gut, known as our microbiome.

It is very humbling to consider that what seems to be emerging as our most powerful leverage point in terms of treating a variety of disease states may well rest in the hands of the hundred trillion bacteria that consider our bodies to be there home. These are the fundamentals of a new horizon in medicine that are explored in my new book, Brain Maker: The Power of Gut Microbes to Heal and Protect Your Brain–for Life.

Finally, in closing, let me state that I fully appreciate that conceptually, my blog postings are clearly becoming a bit more complex in terms of the subjects I am exploring. My mission is to do my very best to make this information understandable, and bring to your attention the health-related relevance of these new scientific discoveries.

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  • This is a fascinating topic. I understand that we have more bacteria than human cells by 10 to 1. This redefines what is means to be a human!

  • francesco

    For some years I used to take one pill a day (a mix of 12 billion bacillus each) but recently I had a bad experience (frequent diarrhea at night) and I stopped. So can anybody tell me what’s the best and correct use of these supplements?